This study was conducted to assess the determinants of plasma concentrations of alpha-tocopherol, bêta-carotene, retinol, and cholesterol fractions in a randomly selected subset of 203 workers participating in a worksite-based health intervention trial.

Workers were from four companies in eastern and central Massachusetts, and all completed an 84-item semiquantitative food frequency questionnaire as part of baseline (preintervention) self-assessment instruments.

At the time of fasting blood sampling, each participant also completed a short screening questionnaire for assessment of changes in dietary habits and tobacco exposure and for collection of data on use of vitamins and nutritional supplements.